This invention relates to an appliance for discharging gaseous, liquid or pasty product, which appliance comprises an inner pouch of deformable non-extensible material for holding the product, an outer enveloping element of caoutchouc-type macromolecular material about the inner pouch, a product outlet associated with the pouch, a valve device for controlling the discharge of product from the pouch through the outlet and being located intermediate the latter and the pouch, and a rigid core associated with the pouch.
In a rapidly increasing number of fields, use is made of sprays for applying products in gaseous, liquid or paste form, for the purpose of body-care, in industry, or even in the kitchen. However, everyone is becoming increasingly more pollution-conscious and, in particular, conscious of the danger of deterioration of the ozone belt which results from the use of means for spraying gases, particularly freon.
On the other hand, the known aerosols present some risk of exploding so that each of them carries a note of precautions that should be taken, for example, that of not placing the aerosol near a source of heat.
Finally, to ensure that the propellant gas cannot pass through them, aerosol sprays have to be made of metal, glass etc., which materials are costly and of a greater weight than plastics material, for example, and require the expenditure of more energy for their production.
In addition, there exist numerous products which cannot be diffused in the form of a spray since they are destroyed by oxidation; these include, for example, food, cosmetic and pharmaceutical products and certain industrial products.
With a view to avoiding all of these problems, a large number of spray appliances that do not use a propellant gas have been proposed. However, none of these known solutions has become firmly established commercially, since they all suffer from more or less serious disadvantages.
Also, the system described in U.S. Pat. No. 566,282, granted on Aug. 18th 1896 to John J. Balley Jr. and mentioning for the first time the use of rubber as an energy-storing means in an atomizer, suffers from the major disadvantage that the product that is present in the container and that has to be expelled is in contact with the rubber, and this greatly limits its use since rubber is chemically unstable when in contact with numerous products. Furthermore, it is not tight to air, spores and bacteria. Apart from this, this atomizer does not enable the product contained therein to be totally expelled since a final proportion thereof that cannot be ejected always remains in the rubber receptacle. Another disadvantage of this system is that neither the expansion nor the compression of the rubber receptacle is controllable, and the vessel is able to assume all shapes, some favorable and some unfavorable to the complete expulsion of the product that it contains.
U.S. Pat. No. 821,875, granted to George M. Kneuper on May 29th 1906, describes means for emptying containers and also makes use of an expansible pouch, which however is stretched along a core which extends into the container and is designed to keep said pouch continuously stretched by holding it in position along the axis of the container. In this way Kneuper partly solved the problem of completely expelling the product without however finding a complete solution. Also, all the problems associated with the use of a rubber container remain unsolved by this spray appliance.
U.S. Pat. No. 2,738,227 of Mar. 13th 1956, granted to G. W. Havens, takes up the ideas disclosed in the two above-mentioned patents and describes an appliance for ejecting a liquid in the form of spray. For this purpose, Havens proposes a core perforated at a large number of points to afford passage to the liquid expelled by the contractive force of a rubber receptacle. It is obvious that this system also suffers from the disadvantage of resulting in a loss of product by non-expulsion, which loss increases with the diameter of the core. Furthermore, if the receptacle is made of natural rubber, its use, as described above, is limited to dealing with a few products, and if the diameter of the core does not make allowance for it, a second loss of product is found to occur, this resulting from final overstretching of the rubber and adding to the lost product remaining in the core.
Numerous other patents, in particular U.S. Pat. Nos. 2,823,953 granted to J. R. George on Feb. 18th 1958, 3,240,399 granted to N. W. Frandeen on Mar. 15th 1966, 3,361,303 granted to C. Jacuzzi on Jan. 2nd 1968, 3,672,543 granted to Plant Industries Inc. on June 27th 1972, and 3,796,356 granted to Plant Industries Inc. on Mar. 12th 1974, describe, with a number of variants, spray appliances utilizing receptacles of elastic materials with or without a core and contained in envelopes and fitted with valves. However, none of these patents describes a spray appliance that is tight to air, spores and bacteria and is unaffected by the product that it is to contain. Furthermore, none of the systems proposed in these patents enables the entire contents of the appliance to be expelled at least approximately linearly during the entire period in which it is used. Apart from this, none of the above-quoted publications describes a spray appliance having a dispensing valve that enables the product to be expelled under pressure in the form of a mist consisting of very tiny droplets.
The same is true as regards the system described in German Patent Application No. 24 42 328 published on Mar. 6th 1975 in the name of Alza Corp., and which describes a container made of synthetic rubber, the inner surface of which may be provided with a covering of likewise elastic rubber which however offers protection against products that would attack the material of the receptacle. In the case of other products, the use of an interior flexible receptacle of synthetic material, for example Mylar, is proposed.
A receptacle made of synthetic rubber of the butyl or nitrile or silicone rubber type results in a very considerable loss of product by non-expulsion because of the fact that synthetic rubbers have a very low permanent elasticity and, after only a few hours under tension, they become overstretched in such a way that a loss of more than 50% of product is incurred. Furthermore, the use of a Mylar film as mentioned above does not result in an air-tight system, and a pouch only be obtained by welding polyethylene to polyethylene, and this means that the layer of aluminium must be on the outside of said receptacle so that it is brought into direct contact with the elastic material. However, unless the coating of aluminium is also plasticized on the exterior, in which case Mylar cannot be used, it breaks down under the high friction effects occurring between the aluminium layer and the elastic material layer both during filling and expulsion of the product, so that the required impermeability of the pouch is adversely affected, since polyethylene alone is not impermeable.
The use of a pouch in plastics material containing a product under pressure is not new. The present inventor has obtained patents in some twenty countries (including Germany, USA and Japan) which are based on the subject-matter of Swiss Pat. No. 484 678, filed on June 27th 1966 and published on Aug. 24th 1968 and describing such a pouch. Furthermore, appliances using a plastics pouch compressed by springs was described and illustrated in a photograph in 1969 in "Lehrbuch und Atlas der Angiologie", Prof. A. Kappert, Editions Hans Huber, Bern. These appliances, which can be used for certain purposes, suffer from the disadvantage of being permeable by aromas and certain germs, so that their applications are limited.
In contrast with the above-mentioned Patents describing a receptacle or pouch of elastic material as a means for storing the energy necessary for expulsion, German Patent Application No. 26 49 722, published on May 5th 1977 in the name of E. I. du Pont de Nemours and Co., describes an elastic fabric obtained by weaving, knotting, crocheting or otherwise uniting elastomeric fibres or filaments with filaments of natural rubber.
This tissue may take various forms including that of a flat envelope. However, if this envelope form is used, it requires means for closing the free end of the envelope so as to prevent it from rising along the inner pouch, or for preventing said inner pouch, if made of rubber, from expanding axially and moving out of the envelope. This can be prevented by means of a core which serves in particular to prevent axial displacement of the envelope towards the valve, and this requires the envelope be closed at its free end so that it can lie firmly against the core.
In this case, the core can be used only in conjunction with an inner elastomeric receptacle having a strong base for the purpose of preventing perforation of the receptacle under the thrust of the envelope; as experience has often shown, a receptacle made of plastics material would not be strong enough and would be pierced.
The various patents mentioned above and numerous other publications illustrate the difficulties in using an elastic material as an element for storing the force required for expelling a product from a container either in the form of spray or any other ejected form. It is known that numerous solutions to the problems enumerated above have been proposed, but they have all had to be rejected for various reasons such as excessively high production costs, over-complicated production methods that are difficult to automatize, the use of materials not suitable for the required application, non-linear delivery, and insufficient comminution of the product which is released in excessively large droplets.
Apart from the spray appliances of the above-described type that do not use a propulsive gas but are fitted with a rubber or plastics element as a source of energy necessary for expelling the product in the container, atomizers are known. This type of spray device cannot be used for all products since, because of the presence of the pumping element, surrounding air and therefore oxygen is pumped into the container, and this is only acceptable in the case of products that are insensitive to oxidation. Furthermore, this atomizer type of spray appliance calls for a certain shape of outer enclosure and requires a change in handling habits on the part of the user of conventional sprays. These appliances are therefore not considered in the following.
The foregoing demonstrates the difficulties encountered in the search for a viable substitute for the conventional aerosol dispenser. These technical difficulties, resulting partially from poor choice of materials and design, are further aggravated by the fact that, to be able to obtain a useful and satisfactory spray appliance which operates without propulsive gas, it is also necessary to take into account the criteria enumerated below.
The prior art shows that the use of a rubber receptacle for accommodating a product and, at the same time, for storing in the wall of the receptacle the force necessary for expelling the product, cannot be achieved, since the only rubber capable of providing an expulsive force that is as linear as possible is natural rubber of the greatest possible degree of purity. However, as stated above this material is not stable, that is to say it does not offer resistance to all products. There is therefore no question of using it as a receptacle for containing the products.